Is there a 'cheap' way to up fuel pressure a couple psi?

[Guest bastaad525]

I know this is bad to even ask... but I'm looking at money on hand vs. money needed to do this swap and I may need to make a compromise or two to get where I"m trying to go. I'm hoping there is some kind of easy, low cost way to up fuel pressure, just a couple psi, just to make sure that I can run 10 lbs of boost w/o leaning out at the top. I know you can run 10 lbs on stock pretty much everything, but everyone who's done so says the engine will definately be lean at high revs, maybe not to the point of detonation, but I dont even want it lean at all. I've heard stuff like, if you put a clamp/zip tie tight around the fuel return line, that could raise pressure, but how much? I've also heard that you can make your own adjustable FPR, but from what, and where could I find instructions on how to do this? I'm figuring I only need to run 44psi for the fuel, I know Yo2001 runs that with 10lbs of boost. I just dont like the idea of paying $200ish to bump up the fuel by what, like 2 psi (I think stock is 42, right?)? That doesn't seem like a good investment for the time being, though I will definately get a real FPR at the latest, when I get an IC, so I can run a bit more boost. Anyone have any tips?

[fl327]

on a properly operating turbo efi setup with the stock turbo, an intercooler, and 10psi, there is no need to bump fuel pressure.

i would get a hot fuel pump just because. i run a bosch porsche 944 unit, run off a relay with 10ga wire, and an adjustable regulator. ive run 10psi with stock fuel pressure, and i often bump the fuel pressure to 50psi or so at the track with a splash of race gas, dont know if it does anything but its hangin tough, hangin tough. i dont even think i need the regulator, but it looks nice and has a guage, so it stays.

[Guest bastaad525]

okay but I dont have an IC yet that's why I'm concerned. I wont have the money to put an IC in for a good long while, so right now it's just bone stock motor, T3 and ECCS/EFI system, with the addition of a boost controller, boost gauge, and blow off valve. I know you can run 10psi on this setup w/o needing an fpr OR better fuel pump (like Jersey), but also know that Jersey felt the car ran a little lean at the top end. I know Tyson, from over on the Zcar.com forums (dont know if he posts here, has an 81 zxt) also tried 10lbs of boost on stock everything, but when he took it to a dyno it showed it was running way lean at the top. I'm thinking an increase in fuel pressure of maybe 2psi would probably cure this problem easily. The high CR N/A motor I run now, when I oringally built that motor and put it back in my '80 ZX, the EFI couldn't compensate and would run very lean at high revs, causing detonation at WOT above 4500rpm. Put in an adjustable FPR and raised the pressure by 2 lbs and it totally got rid of the detonation..... so 2psi of fuel seemed to make a huge difference. Is there no way to get 2psi more through the stock injection, w/o having to buy a new fuel pump or adjustable fpr?

[DAW]

I believe a fixed orfice in the return line should bump it up. Use a fuel pressure guage to know where you're starting from and how much you change pressure by the size of the restrictor selected. DAW

[Doug71zt]

I crushed the stock FPR on my car to increase the fuel pressure a couple years ago - It was a stop-gap until I could get new injectors, rail, pump and reg. It increases the spring pressure on the diaphram. No accurate way to do it except crush a little, check fuel pressure, then crush a little more. All bets are off with this mod - get a couple FPR's at the pickandpull and go crazy. You crush the top cap between the joint on the case and the top of the can. Hondas and Chev have kits that you can cut off the top of the FPR and clamp the adjuster on the top to get adjustment - don't know if any will fit the Nissan FPR. I guess you could check the diameter of a camaro FPR. I run a Hyundai Accent FPR now - base line is 42 psi. I think that stock Nissan is 36-38psi. Good Luck - Doug

[fl327]

two of some of my favorite old school tricks-the crushed regulator and the restrictor in the return line, gotta love it.

i cant see going lean at 10psi with a intercooled turbo setup,

when i first set car up with 3" exhaust, i was reading 9psi on the freeway, and 7.5-8psi street driving, i bumped it to ten a few times, it was fine, this was with no intercooler. with an intercooler, and 10psi its fine too, i just dont want to play with it too much until the weather gets a little colder.

[yo2001]

my car is fine at 10 psi but it was still lean on dyno with WB

[Guest bastaad525]

Yo2001.... WB?? I know I should know what this means but uh.... I dont You use abbreviations a lot! Thanks for the tips guys, if anyone else has any, keep them coming please. I was thinking about crushing the FPR... it occured to me when I was reading an article about BOV's, and how people crush the cap on 1g dsm bov's to get them to hold more boost... I figured the diaphram inside of the FPR was probably similiar and could be effected in a similiar way, but wasnt sure if crushing it would raise or lower the psi at the injectors. Without seeing a picture of an example, I dont think I'd try this mod though, too much chance I'd f' if up. So clamping off the return line DOES work?? I might take my chances trying to find that hyunai regulator, that sounds like it might work perfectly. If the stock pressure is 36-38 than 42 should be perfect.

[SleeperZ]

If you are not even running an intercooler, 10 psi boost will not run lean. You will not pull in enough air for the ECU to max out duty cycle. Now 12 psi intercooled will start to run lean, but until you start putting down 220+ rwhp, don't worry about it.

[yo2001]

10psi, stock turbo, IC, and 3in DP I trapped 100.5mph. with 2800lb car (with me in it ) caculated 222WHP.

[Lockjaw]

WB=wideband

 

HAHA, I couldn't resist.

[Lockjaw]

Oh and I crushed a fpr once, and promptly had to go buy a new one.....so if money is tight, you may want to try something else.

[Guest bastaad525]

heheh yeah like I said.... I dont want to even try it w/o at least seeing an example, I know I'll kill it.

[Guest bastaad525]

Okay, so what Sleeper is saying is the boost level isn't really the relevant #, the stock EFI should be good for up to about 220 rwhp before running too lean? That sounds pretty good... dont think I'm gonna be putting out that much power, hoping for around 200 even.... you guys think I'll get more or less?

[cygnusx1]

This was on my Weber fed Alfa Romeo. I converted from Mechanical FI to used dual Weber Carbs ($60 from a junkyard with manifold) and left the FI fuel pump in. Since the Webers only want about 3psi, I put in a full flow return loop to the tank and wrapped one spot on the return line with electrical tape, slipped an IDEAL hose clamp over the tape, and tightened the clamp on the return line untill I saw 3psi at the Carbs.

 

Gotta love those college days with no money.

 

It worked for over 2 years that way. Rust killed it.

[Guest bastaad525]

When ever I get down to a dyno with this new motor, probably will be a while, I'll see what happens with the boost at 10psi, on the wideband. If it leans out at all at the top end I might try the hose clamp trick since I'll be able to see what effect it has..... while I'm not in college these are the days of having no money.... every penny I've got is going into this turbo conversion so the sooner it's done the better, any extra money I can avoid spending is great even if it means a little mickey mousing along the way.